What is Stack?

In poker, the stack is the total chips a player has in front of them at the table, available to bet on the current hand. Stack depth is almost always measured in big blinds rather than currency, because that ratio determines correct strategy: a '100 big blind stack' in a £1/£2 game is £200, and that depth tells you far more than the cash figure alone. The key concept is the effective stack — in any hand between two players, the smaller of the two stacks, because that is the maximum either can win or lose against the other. Worked example: you hold £500 and your opponent holds £150 in a £1/£2 game. The effective stack is £150 (75 big blinds), so no matter how strong your hand, £150 is the most you can win from that player; your extra £350 is irrelevant to this confrontation. If a third player with £900 enters, your effective stack against them is your own £500. Stack depth dictates style. Deep stacks (150+ big blinds) reward post-flop skill, implied odds and patient play, because there is room to manoeuvre across multiple streets. Short stacks (under ~25 big blinds) compress decisions into pre-flop push-or-fold spots, where the maths of shoving all-in dominates. The common mistake is ignoring the effective stack and over-valuing a monster hand when the opponent is short — you simply cannot extract chips that are not there. Always read the effective stack before committing. Compare with all-in, big blind and chip leader, and note that stack sizing also shapes ICM decisions late in tournaments.